included dispersed forms and aggregates (diameters > 4-5 pm) . The 

 protozoa, belonging, probably, to at least 2 trophic levels, were 

 subdivided into small heterotrophic flagellata (diameters - 3-5 pm) , 

 feeding on small phytoplankton and dispersed bacteria, and infusoria, 

 feeding on phytoplankton, bacteria and flagellata. The mesozooplankton 

 was subdivided into 2 trophic levels: omnivores with primarily filter- 

 type feeding, consuming phytoplankton, bacteria and protozoa and 

 catching predators, consuming infusoria, omnivores and animals of their 

 own level. The omnivores included: fine filter feeders (appendicularia 

 and doliolids), the primary food of which consisted of small 

 phytoplankton, bacteria and flagellata; small copepoda (nauplii, 

 copepodites of copepoda and mature calanoida measuring up to 1 mm), 

 feeding on phytoplankton, aggregated bacteria and protozoa; 

 nonpredaceous large calanoida ( Undinula , Eucalanus , Nannocalanus , etc.), 

 consuming phytoplankton, aggregated bacteria and infusoria. The 

 mesoplanktonic carnivores were represented by: cyclopoida, the food for 

 which consisted of the infusoria, fine filter feeders and small 

 copepoda; predaceous calanoida ( Euchaeta , Candacia , etc.), feeding on 

 fine filter feeders, small copepoda, and cyclopoida; other carnivores 

 (primarily chaetognatha, polychaeta and hyperiids), consuming all 

 omnivores, cyclopoida and predaceous calanoida. 



The rate of production of the lower trophic levels (phytoplankton 

 and bacteria) decreased with decreasing trophicity of the water from 18 

 (phytoplankton) and 6.6 Kcal/m^*day (bacteria) in the zone of most 

 intensive upwelling (97°W) to 3.2 and 2.3 Kcal/m^-day at 140°W. For the 

 mesozooplankton, and particularly the predaceous forms, this decrease 

 was less strongly expressed. For example, for the cyclopoida, the rate 

 of production decreases from 0.7 to 0.1, while for all predators except 

 copepoda, it decreases from 0.4 to 0.1 Kcal/m'^'day. The specific 

 production (mean daily P/B coefficients) for the phytoplankton and 

 bacteria increase as the water becomes poorer, decreasing for the 

 protozoa and mesozooplankton. 



It has been repeatedly stated that a young community, forming in 

 the eutrophic waters of an upwelling, accumulates energy, and then, as 

 the community develops, the water "ages" and the trophicity decreases, 

 the energy is expended (Vinogradov et al . , 1971). The data obtained in 

 the equatorial eastern Pacific allow us to explain the mechanism of this 

 process. As we move from east to west along the zonal component of the 

 surface equatorial current, the trophicity of the water and biomass of 

 all primary groups of microplankton and mesoplankton decrease, 

 particularly that of the phytoplankton and bacterioplankton. The degree 

 of satisfaction of the food demands decreases, the stress of trophic 

 connections increases and the effectiveness of energy transfer through 

 the system increases. The significance of predators increases, and 

 cannibalism increase, both within groups of protozoa, and within groups 

 of predaceous mesozooplankton--from 50 to 80% of the production of 

 zooplankton and almost all of the production of protozoa are consumed by 

 individuals at the same trophic level. As a result, the total and 

 specific daily production of these groups and of all zooplankton take on 

 negative values. The very expenditure of energy mentioned above 

 actually occurs. True enough, the trophic pressure on phytoplankton and 



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